7941 No Ethernet

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Dec 4th, 2007
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Just recieved a 7941G phone. Currently have a 7940 on my desk, PoE. When I try to plug in the 7941 to the network (using the same cable as the 7940), nothing... no power, nothing. I have a spare power cube, so I plugged the 7941 in using that, and the "Ethernet Disconnected" message displays. Plug my 7940 back in and it powers up and registers fine.


Am I missing something?

Correct Answer by Zin.Karzazi about 9 years 6 months ago


had the same issue last week, phone just keep displaying "Ethernet Disconnected", the cable was fine but the RJ-45 port labelled “network” was not, so RMA is your friend :).

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Rob Huffman Tue, 12/04/2007 - 16:46
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Hi Ben,


This really sounds like a cable issue. When you plugged the Power Cube in and received the "Ethernet Disconnected" message on the display, you have proven part of the puzzle (that the existing cable that went from the wall jack to the 10/100SW on the base of the phone is not connecting for some reason):) Try isolating and replacing all the cables involved and probably even leave the PC cable out of the equation.


You should be fine for power as both the 7940 and 7941 are Class 2 devices. Have a look;


The 7940G/7941G and 7960G/7961G are class 2 devices (7.7 watts) and the 7941G-GE/7961G-GE phones are class 3 devices (15.4 watts).These are not configurable settings.


Have a look;


7910/7940/7960 Power requirements;


http://www.cisco.com/en/US/products/hw/switches/ps708/products_installation_guide_chapter09186a008020e088.html#wp1008467



Hope this helps!

Rob

benharned Thu, 12/06/2007 - 05:53
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You suspect the cable even though it works for my 7940?

paolo bevilacqua Thu, 12/06/2007 - 05:58
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Hi,


Most likely my friend Rob is correct. The 7941 uses a different PoE standard (.af Vs. cisco proprietary) and this can have triggered some kind of deficiencies in cabling.

benharned Thu, 12/06/2007 - 06:26
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So which standard is the 7941 using? (and you're saying the 7941 is different than the 7940?


These are running to a 3550, does that play to the equation at all?

Rob Huffman Thu, 12/06/2007 - 06:40
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Hi Ben,


The 7940 uses only Cisco Pre-Standard PoE whereas the 7941G can use either Cisco Pre-Standard PoE or the new standard IEEE 802.3af PoE. The reason that I think the problem is perhaps with the cable is because of the report on the 7941 display that indicated "ETHERNET DISCONNECTED" used the external power supply. This is really just a suggested step here in trying to Troubleshoot the issue. It seems "odd" that this could be the case but I have seen stranger things happen. I have also plugged the cables into the wrong Jacks on the base of the phone and gone on to try and solve this problem only to realize what an idiot I am sometime later :)


Power Requirements The phone is interoperable with Cisco Pre-standard PoE and with IEEE 802.3af PoE (the phone is a Class 2 device); 48 VDC is required; it can be supplied locally at the desktop using an optional AC-to-DC power supply (part number CP-PWR-CUBE-3=).

From this good doc;


http://www.cisco.com/en/US/products/hw/phones/ps379/products_data_sheet0900aecd802ff012.html


Hope this helps!

Rob

Correct Answer
Zin.Karzazi Thu, 12/06/2007 - 06:32
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had the same issue last week, phone just keep displaying "Ethernet Disconnected", the cable was fine but the RJ-45 port labelled “network” was not, so RMA is your friend :).

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